Regarding the 'elite schools' - Perhaps it is the critical thinking that gives children the real advantage - perhaps not the IQ.
Off piste a little again - My own education was very poor and passive, but I have good analytical skills. These were developed mostly by discussions at home, overheard as I was growing up between my father and friends who would come round and debate the issues of the day.
My father's own education was classical and traditional with lots of rote learning, forced by punishment at a state run boarding school. He then went on to teach 'remedial' children as they used to call them - an attempt to rebel against his own harsh education.
His own critical thinking/debating skills developed from a massive knowledge base in complex areas, particularly philosophy and history. Where I found him lacking was in picking apart the media, he often couldn't spot where stories were pushed from an angle. He was easily led by campaigns.
This is the aspect of education I think is essential in the modern world - that children are taught to read newspapers and mobile phone contracts to see the catch, or the bias without jumping to conspiracy theories but with clarity.
Interesting that the non-questioning education system of Dad's era preceded the era of propaganda campaigns that led to the genocides of war.
Interesting also that our modern, complacent education system has led to millions of people in debt, committed to contracts they don't understand the implications of and a monetary system that only bankers understand.
Knowledge is definitely power, regardless of how you gain it, but understanding that knowledge and picking it apart is true power.